MUSHROOMS. 173 



Desmidittm, Achnanthes, Gomphonema, Exilaria, Fragillaria, Micromega, Beckleys, 

 Cymbella, Navicula, and Euastrum. 



Confervas also inhabit both salt and fresh waters, but are commonly of an olive, 

 violet, and red, rather than a green colour. They consist of a series of cells of various 

 forms, as cylindrical tubular globes, or elliptical, and grow by the subdivision of their 

 cells, and the propagation of spores within the cells. Their forms are extremely varied, 

 and their distribution almost universal. The Protococcus, Hsematococcus, Porphyra 

 (stewed and eaten, as Lava), Ulva, Common Nostoc, or Star-jelly, Palmella, Con- 

 ferva, and Penicillum, are genera commonly known. 



FueuS) or Sea- weeds, are closely connected with Confervas both in structure and situ- 

 ation. They differ in fheir mode of reproduction, for the reproductive organs are situate 

 without the plant, appearing as little green worts invested by a thin membrane ; and 

 the male organs, or antheridia, have the spiral filament, before described under the 

 head of Mosses. Some of them are eatable, and are eaten by various people in the 

 Pacific, as well as in the instances of the Alaria -ZEsculenta, and Fucus Vesiculosus, by 

 the inhabitants of Ireland, Scotland, and the northern islands. They are, however, 

 of still greater use to man by affording soda in the impure form of kelp, which is used 

 largely by soap makers and glass manufacturers, and also iodine, which is yielded by 

 many genera, but more particularly by the Ecklonia Buccinalis of the Cape of Good 

 Hope, and by many on our own shores. 



Rosetangles (Ceramiceae) or the Corallines, are also Sea-weeds, but usually have a 

 rose or purplish colour. They consist of cells of various forms, arranged in one or 

 more rows, so as to produce an articulated frond, and are propagated by spores formed 

 in threes or fours within a mother cell. They are entirely marine ; and yield a greater 

 number of genera, which are edible by man or animals, than any other form of Sea- 

 weeds. Of the edible ones we may instance Plocaria compressa and Chondrus crispus, or 

 Carrigeen Moss; Rhodomenia palmata, or Dulse; Iridcsa edulis ; and the Laurencia 

 pwnatifida, or Pepper Dulse. The Plocaria tenax yields glue and varnish, used by the 

 Chinese in the manufacture of their lanthorns ; the Chondrus crispus yields size ; and 

 the Rytiphlaa tinctoria produces a valuable dye. This is a very valuable class of 

 plants. 



The Charas are submersed plants of a green colour, with regularly-branched brittle 

 stems and whorls of small branches or leaves. In some of these, as the Nitella, the 

 circulation may be Been in its progress up and down the stem by the aid of the 

 microscope. 



MUSHROOMS. 



The general term Fungi represents the varied members of this extensive class of 

 plants, but very inadequately, since the class comprehends, besides the true Mushrooms 

 or Fungi, Moulds, Morels, Mildews, Blights, and Puff-balls. The members, therefore, 

 vaiy from a size so minute as to be almost or quite invisible to the naked eye, to a mass 

 much larger than the human head. They grow, for the most part, upon decaying sub- 

 stances, and usually increase in size from within. A few, as the Agaricus fastens, are 

 said to possess lactiferous vessels and spiral filaments. The major part of them are, 

 moreover, very ephemeral in their character. Some of them are edible, as the common 

 Mushroom (Agaricus campestris), Helvella or Morel, and Tuber or Truffle, all of 

 which, with some others, are commonly eaten both in this country and on the Conti- 



